diff --git a/clippy_utils/src/ty/type_certainty/mod.rs b/clippy_utils/src/ty/type_certainty/mod.rs index 20bb0d44c59a..d9c7e6eac9f6 100644 --- a/clippy_utils/src/ty/type_certainty/mod.rs +++ b/clippy_utils/src/ty/type_certainty/mod.rs @@ -16,7 +16,7 @@ use rustc_ast::{LitFloatType, LitIntType, LitKind}; use rustc_hir::def::{DefKind, Res}; use rustc_hir::def_id::DefId; use rustc_hir::intravisit::{InferKind, Visitor, VisitorExt, walk_qpath, walk_ty}; -use rustc_hir::{self as hir, AmbigArg, Expr, ExprKind, GenericArgs, HirId, Node, PathSegment, QPath, TyKind}; +use rustc_hir::{self as hir, AmbigArg, Expr, ExprKind, GenericArgs, HirId, Node, Param, PathSegment, QPath, TyKind}; use rustc_lint::LateContext; use rustc_middle::ty::{self, AdtDef, GenericArgKind, Ty}; use rustc_span::Span; @@ -215,6 +215,20 @@ fn qpath_certainty(cx: &LateContext<'_>, qpath: &QPath<'_>, resolves_to_type: bo certainty } +/// Tries to tell whether `param` resolves to something certain, e.g., a non-wildcard type if +/// present. The certainty `DefId` is cleared before returning. +fn param_certainty(cx: &LateContext<'_>, param: &Param<'_>) -> Certainty { + let owner_did = cx.tcx.hir_enclosing_body_owner(param.hir_id); + let Some(fn_decl) = cx.tcx.hir_fn_decl_by_hir_id(cx.tcx.local_def_id_to_hir_id(owner_did)) else { + return Certainty::Uncertain; + }; + let inputs = fn_decl.inputs; + let body_params = cx.tcx.hir_body_owned_by(owner_did).params; + std::iter::zip(body_params, inputs) + .find(|(p, _)| p.hir_id == param.hir_id) + .map_or(Certainty::Uncertain, |(_, ty)| type_certainty(cx, ty).clear_def_id()) +} + fn path_segment_certainty( cx: &LateContext<'_>, parent_certainty: Certainty, @@ -267,8 +281,9 @@ fn path_segment_certainty( // `get_parent` because `hir_id` refers to a `Pat`, and we're interested in the node containing the `Pat`. Res::Local(hir_id) => match cx.tcx.parent_hir_node(hir_id) { - // An argument's type is always certain. - Node::Param(..) => Certainty::Certain(None), + // A parameter's type is not always certain, as it may come from an untyped closure definition, + // or from a wildcard in a typed closure definition. + Node::Param(param) => param_certainty(cx, param), // A local's type is certain if its type annotation is certain or it has an initializer whose // type is certain. Node::LetStmt(local) => {